The inmate population of state and federal prisons increased
significantly after 1980.

Before the 1990s, imprisonment rates of more than 400 inmates per 100,000
population
had never been approached in the United States or any other developed
nation. As the chart shows, the U.S. inmate population more than tripled in the
last two decades of the century, reaching 462 per 100,000 population in 1999.

The ethnic, gender, and age distributions of prison inmates differed greatly from
those of the general population. At the end of 1997, according to a Bureau of
Justice Statistics estimate, 48 percent of state and federal prisoners were white, 49
percent were black, 2 percent were American Indian, and 1 percent were other
races. Hispanics, who may be of any race, constituted 18 percent of state and
federal
prisoners. Women composed about 6 percent of the prisoner population,
twice the female share of inmates in the early years of the century. The
overwhelming
majority of prisoners were between the ages of eighteen and fifty-four,
with a concentration around age thirty.

These inmate characteristics produced enormous variations in the imprisonment
rates of subgroups of the population. In 1996, for example, the imprisonment
rate among eighteen- to fifty-four-year-olds ranged from 59 per 100,000 white
women to 6,286 per 100,000 black men.

At the end of 1998, 123,041 inmates were in the federal prison system, and
1,178,978 inmates were in state prisons. In addition, almost 600,000 were
confined
in local jails, where they were awaiting trial, serving short sentences, or
waiting for prison space.

Among the factors contributing to the increase in the inmate population were the
enhanced prosecution of drug offenses, longer sentences for common crimes, and
reduced access to parole and probation.